Forcing specific GPU under Wayland and Vulkan

[Jaakkonen]

There are plenty of problems while using Nvidia+wgpu+Vulkan combination which are really hard to work around since running (at least some) applications using iced don't honor WGPU_ADAPTER_NAME, WGPU_POWER_PREF, __VK_LAYER_NV_optimus=non_NVIDIA_only, __NV_PRIME_RENDER_OFFLOAD=1 or __GLX_VENDOR_LIBRARY_NAME=mesa environment variables normally used to force WGPU to use an Intel iGPU instead of a dGPU.

However the Vulkan libraries always check for installable client drivers (ICD) from /usr/share/vulkan/icd.d/ and the specific files can also be overridden by VK_ICD_FILENAMES environment variable with : or , as the path separator. With these one can force the application to only find Intel Vulkan drivers for instance (VK_ICD_FILENAMES=/usr/share/vulkan/icd.d/intel_icd.x86_64.json) and be sure that the application won't be using Nvidia.

The reason to run applications under Intel iGPU except for Nvidia dGPU on for example dell laptops is that the image buffers for photos don't move around correctly and you only get black rectangles where the images are supposed to be.